Etized mice showed better overall cognitive performance (time trial) beginning on day three, and better degree of learning (omission errors and wrong choices) beginning on day two. Starting from day six, anesthetized showed a less anxious behavior (board entries).Sevoflurane anesthesia does not affect LTP after 24 hTo evaluate the possibility that sevoflurane anesthesia could affect synaptic plasticity, LTP was studied in hippocampal slices of anesthetized and Title Loaded From File non-anesthetized mice one day after anesthesia or sham treatment. Delivering HFS induced LTP of fEPSP slopes, which was not significantly different between slices of anesthetized (sev) or non-anesthetized (sham) mice (relative fEPSP slopes sev: 149.669.4 (n = 9); sham: 159.569.4 (n = 10; P = 0.48); Fig. 2).Expression of NMDA receptor subunit type 1 and 2B is upregulated after sevoflurane anesthesiaSevoflurane anesthesia might induce adaptational changes in the expression levels of neurotransmitter receptor subunits. We used western blotting for profiling the expression levels of the NMDA receptor type 1, type 2A and type 2B subunits (NR1, NR2A, and NR2B), subunits of a-amino-3-hydroxy-5-methyl-4isoxazole-propionic acid (GluR1, GluR2/3, GluR4), kainate (GluR6/7), GABAA (a2), and nicotinic acetylcholine (b2) receptors in hippocampi of anesthetized and non-anesthetized mice (Fig. 3). In homogenates of the hippocampi of anesthetized mice, we found an upregulation of the NR1 subunit (153617 of control, n = 11, P = 0.01) and the NR2B subunit (177631 of control, n = 11, P = 0.03). The expression levels of the other receptor subtypes did not change significantly (Fig. 3).Sevoflurane Anesthesia and Learning and MemoryFigure 1. Mice that underwent a sevoflurane anesthesia showed better cognitive performance. On days one to eight after undergoing a sevoflurane anesthesia (sev) or sham treatment (sham), cognitive performance and behavorial parameters were assessed using the modified hole board test, a task in which the animals are trained to search for food rewards hidden in marked cylinders. A: Time that each animal required for performing the trial plotted against time. B: Number of marked and Title Loaded From File baited holes, which were not visited at all during one trial (left) and number of non-marked holes which were visited (right) plotted 23148522 against time. C: Number of times the mouse enters the board plotted against time. D: Number of times the mouse crossed the marked lines per minute plotted against time. Each group consisted of 24 animals. Each symbol represents averaged data from four trials per day. * p,0.05 reveals better cognitive performance (beginning on day three) and better learning (beginning on day two), as well as an attenuated anxiety-related behavior (beginning on day six) in anesthetized mice. doi:10.1371/journal.pone.0064732.gDiscussionThe aim of the present study was to determine medium-term effects of sevoflurane anesthesia on cognitive performance, LTP, and receptor subunit expression in mice. We found that an anesthesia with sevoflurane, applied at a clinically relevant concentration, improved cognitive performance, but had no effect on hippocampal LTP. The improved cognitive performance might be explained by 1676428 the elevated expression levels of the NR1 and NR2B subunits in the hippocampus. In the present study, we could see an improvement of hippocampus-dependent cognitive performance in animals that were anesthetized. This improvement has been observed starting from day two lasting.Etized mice showed better overall cognitive performance (time trial) beginning on day three, and better degree of learning (omission errors and wrong choices) beginning on day two. Starting from day six, anesthetized showed a less anxious behavior (board entries).Sevoflurane anesthesia does not affect LTP after 24 hTo evaluate the possibility that sevoflurane anesthesia could affect synaptic plasticity, LTP was studied in hippocampal slices of anesthetized and non-anesthetized mice one day after anesthesia or sham treatment. Delivering HFS induced LTP of fEPSP slopes, which was not significantly different between slices of anesthetized (sev) or non-anesthetized (sham) mice (relative fEPSP slopes sev: 149.669.4 (n = 9); sham: 159.569.4 (n = 10; P = 0.48); Fig. 2).Expression of NMDA receptor subunit type 1 and 2B is upregulated after sevoflurane anesthesiaSevoflurane anesthesia might induce adaptational changes in the expression levels of neurotransmitter receptor subunits. We used western blotting for profiling the expression levels of the NMDA receptor type 1, type 2A and type 2B subunits (NR1, NR2A, and NR2B), subunits of a-amino-3-hydroxy-5-methyl-4isoxazole-propionic acid (GluR1, GluR2/3, GluR4), kainate (GluR6/7), GABAA (a2), and nicotinic acetylcholine (b2) receptors in hippocampi of anesthetized and non-anesthetized mice (Fig. 3). In homogenates of the hippocampi of anesthetized mice, we found an upregulation of the NR1 subunit (153617 of control, n = 11, P = 0.01) and the NR2B subunit (177631 of control, n = 11, P = 0.03). The expression levels of the other receptor subtypes did not change significantly (Fig. 3).Sevoflurane Anesthesia and Learning and MemoryFigure 1. Mice that underwent a sevoflurane anesthesia showed better cognitive performance. On days one to eight after undergoing a sevoflurane anesthesia (sev) or sham treatment (sham), cognitive performance and behavorial parameters were assessed using the modified hole board test, a task in which the animals are trained to search for food rewards hidden in marked cylinders. A: Time that each animal required for performing the trial plotted against time. B: Number of marked and baited holes, which were not visited at all during one trial (left) and number of non-marked holes which were visited (right) plotted 23148522 against time. C: Number of times the mouse enters the board plotted against time. D: Number of times the mouse crossed the marked lines per minute plotted against time. Each group consisted of 24 animals. Each symbol represents averaged data from four trials per day. * p,0.05 reveals better cognitive performance (beginning on day three) and better learning (beginning on day two), as well as an attenuated anxiety-related behavior (beginning on day six) in anesthetized mice. doi:10.1371/journal.pone.0064732.gDiscussionThe aim of the present study was to determine medium-term effects of sevoflurane anesthesia on cognitive performance, LTP, and receptor subunit expression in mice. We found that an anesthesia with sevoflurane, applied at a clinically relevant concentration, improved cognitive performance, but had no effect on hippocampal LTP. The improved cognitive performance might be explained by 1676428 the elevated expression levels of the NR1 and NR2B subunits in the hippocampus. In the present study, we could see an improvement of hippocampus-dependent cognitive performance in animals that were anesthetized. This improvement has been observed starting from day two lasting.
